A keyboard is one of the widely-used computer peripheral devices. Via the keyboard, the user may input characters or commands into a computer. FIG. 1 is a schematic top view illustrating the outward appearance of a conventional keyboard. As shown in FIG. 1, the conventional keyboard 1 comprises plural keys 10. When one of these keys 10 is depressed by the user's finger, a corresponding signal is transmitted from the keyboard 1 to the computer, so that a corresponding key function is implemented by the computer. For example, by depressing the key 101, a corresponding English letter or a corresponding symbol is inputted into the computer. By depressing the key 102, a corresponding number is inputted into the computer. Moreover, by depressing the key 103, a corresponding programmed function is quickly executed.
With increasing development of science and technology, the keyboard manufacturers make efforts in designing novel keyboards with diversified functions in order to meet the requirements of different users. Recently, an illuminated keyboard with an illuminating function has been introduced into the market. Consequently, in a case that the illuminated keyboard is used in the dim environment with insufficient luminance, the characters marked on the keys of the illuminated keyboard are still clearly visible to the user.
Since the outward appearance of the conventional illuminated keyboard is similar to the outward appearance of the conventional keyboard 1, only the inner structure of the conventional illuminated keyboard will be illustrated in more details as follows. FIG. 2 is a schematic cross-sectional view illustrating a conventional illuminated keyboard.
Hereinafter, the components of the conventional illuminated keyboard will be illustrated with reference to FIG. 2. As shown in FIG. 2, the conventional illuminated keyboard 2 comprises at least one key 21, a membrane switch circuit module 22, a base plate 23, and a backlight module 24.
The key 21 comprises a keycap 211, an upward/downward supporting member 212, and an elastic element 213.
Moreover, the membrane switch circuit module 22 comprises an upper wiring plate 221 and a lower wiring plate 222. An upper contact 221a is formed on the upper wiring plate 221. Corresponding to the upper contact 221a, a lower contact 222a is formed on the lower wiring plate 222.
Moreover, the backlight module 24 comprises a light guide plate 241, a reflective plate 242, and a light-emitting element 243.
An assembling method and the operating principle of the conventional illuminated keyboard 2 will be illustrated in more details as follows. Firstly, both of the key 21 and the membrane switch circuit module 22 are disposed on the base plate 23, and the backlight module 24 is disposed under the base plate 23.
In particular, the upward/downward supporting member 212 of the key 21 is connected with the keycap 211 and the base plate 23. The elastic element 213 is disposed within the upward/downward supporting member 212, and arranged between the keycap 211 and the base plate 23. The membrane switch circuit module 22 is arranged between the elastic element 213 and the base plate 23.
As the key 21 is depressed, the keycap 211 is correspondingly moved with the upward/downward supporting member 212 in a vertical direction toward the base plate 23, and the membrane switch circuit module 22 is pushed by a protrusion part 213a within the elastic element 213. Under this circumstance, the upper contact 221a and the lower contact 222a of the membrane switch circuit module 22 are contacted with each other to be electrically conducted. Consequently, a corresponding input function is executed. Moreover, the elastic element 213 also provides an elastic force for allowing the keycap 211 to be moved upwardly or downwardly relative to the base plate 23.
Moreover, the light guide plate 241 is disposed under the base plate 23. The reflective plate 242 is disposed under the light guide plate 241. The light-emitting element 243 is located at a side of the light guide plate 241. The light-emitting element 243 is used for providing a light beam to illuminate the illuminated keyboard 2. After the light beam emitted by the light-emitting element 243 is incident into the light guide plate 241, the light beam is guided by the light guide plate 241 to be projected onto the base plate 23. Moreover, the light beam from the light-emitting element 243 may be reflected by the reflective plate 242, so that the light beam is transferred within the light guide plate 241 more uniformly.
From the above discussions, the keycap 211, the upward/downward supporting member 212, the elastic element 213, the membrane switch circuit module 22, the base plate 23, the light guide plate 241 and the reflective plate 242 of the conventional illuminated keyboard 2 are sequentially arranged and assembled from top to bottom.
However, the conventional illuminated keyboard 2 still has some drawbacks. Firstly, since the light guide plate 241 is located at the relatively lower layer of the conventional illuminated keyboard 2, the portion of the light beam transmitted upwardly through the light guide plate 241 to be projected onto the keycap 211 is influenced by the plural overlying substrates and difficultly controlled. Moreover, the elastic element 213 is mainly used to press the membrane switch circuit module 22 in order to make electrical connection between the upper contact 221a and the lower contact 222a. Consequently, the protrusion part 213a within the elastic element 213 is an essential component. Due to the protrusion part 213a, the shape of the elastic element 213 is restricted and fails to be changed at will. Due to the shape of the elastic element 213, the light beam is readily projected to other places instead of the keycap 211. Under this circumstance, the luminance of the keycap 211 is adversely affected, and the light beam projected onto the keycap 211 fails to be uniformly distributed.
Therefore, there is a need of providing an improved illuminated keyboard in order to eliminate the above drawbacks.